Greater New Orleans

About 4,000 feet of earthen levee is being raised near U.S. 11 in eastern New Orleans after it sank below the level necessary to block overtopping of storm surges caused by a 100-year hurricane.
(Army Corps of Engineers)

The Army Corps of Engineers is spending $1.3 million to raise about 4,000 feet of earthen levee in easternmost New Orleans that has subsided so low it wouldn't be able to withstand a storm surge caused by a so-called 100-year hurricane.

Included in the reconstruction is a 1,500-foot-long section on either side of U.S. 11 on the edge of the Bayou Sauvage National Wildlife Refuge and smaller areas between U.S. 11 and Interstate 10, and one small area just north of U.S. 90 in the same area, said corps Senior Project Manager Chris Gilmore.

The corps expected this area to settle significantly in a relatively short amount of time, and Gilmore said and "surveys of the reach (will) be taken annually for the first few years." The repair will raise the levee for at least five to 10 years, he said. After that, he said, "a lift may be required to maintain the 100-year elevation." The levee was actually "overbuilt," raised to between 18 1/2 and 19 feet, or 1 1/2 to 2 feet above the 100-year level, and is being raised to that level again.

The biggest area of sinking occurred where rapidly subsiding soils were expected because they lie on top of an ancient slough, or depression, that was once a stream or river bed. The corps had installed a large field of wick drains that were designed to speed the removal of water from the soils. The drains were not affected by the rapid sinking, Gilmore said.

A nearby segment of levee over which a portion of the eastbound and westbound lanes of I-10 were rebuilt did not sink, he said.

The work is being done by a crew hired by the corps. The repairs were
delayed for several weeks because high water in the Mississippi River
limited the use of fill mined from the Bonnet Carre Spillway, which was
partially flooded by water leaking through the spillway structure.

View full sizeWhen the permanent pumping station is built at the Lake Pontchartrain end of the 17th Street Canal, these diesel-fueled temporary pumps, photographed in August 2011, will be dismantled. Rusty Costanza, NOLA.com |The Times-Picayune archive

On Monday, the corps had to conduct an emergency cleanup of about 40 gallons of diesel fuel that spilled into the 17th Street Canal when a valve failed at a diesel generator at the temporary gate and pumps structure at the canal's mouth.

The spill was reported Monday at 4 p.m. and was cleaned up by 8 p.m., according to an email from corps project manager Donald Schneider.

"The diesel fuel was contained within our spill containment booms," Schneider wrote. "The failed valve was secured and the spill was cleaned up" by 8 p.m, he said.

The temporary pumps have been in place since June 2006, and will continue to be used until completion of a permanent canal closure and pumps structure at the canal's mouth. Preconstruction work for the structure is under way, and construction should begin this fall.